Field of the Invention
The present invention relates to a data synchronizing system that synchronizes data of a plurality of devices connected via a network, a method for controlling the data synchronizing system, an authorization server, and a storage medium for the data synchronizing system.
Description of the Related Art
According to one of recently available services, it is feasible to synchronize data among a plurality of devices via a system accessible via the internet. For example, as discussed in Japanese Patent Application Laid-Open No. 2011-065542, there is a service available to transfer dictionary information to all devices owned by a user when the dictionary information is updated. Further, as another service available when a photo is stored in a device, it is feasible to transfer the stored photo to other devices owned by a user. For example, Photo Stream is available to iCloud (registered trademark of Apple Inc.) users.
However, such a data synchronization service is not usable to realize data synchronization among a plurality of devices unless a list of devices owned by a user is acquired beforehand by the data synchronization service. According to the above-mentioned conventional services, each user is initially required to register a user own device list to the service so that the service can acquire the registered user own device list.
However, according to the above-mentioned method, it is unfeasible to provide the user own device list to a plurality of services. Therefore, each user is required to register own devices to each service. When a user adds or deletes a device, the user updates the user own device list for each of the plurality of services. Repeating the above-mentioned device adding or deleting operation for each service is troublesome when the user uses a plurality of data synchronization services.
Further, as another problem, there will be a higher risk of leaking information when a plurality of services manages a user own device list in a decentralized fashion. In many cases, if the decentralized management of the user own device list is performed among two or more services, the security measure will be independently determined by each service. If the service has a problem in the security measure, there will be a possibility of unintentionally leaking the user own device list. Further, providing the user own device list to other persons without any permission of the user may occur.